This invention relates to a rotor blade assembly for a helicopter, and more particularly to a leading edge weight assembly for a helicopter rotor blade which provides substantially fail-safe retention of the weight segments.
It is well known in the art that aerodynamic rotor blades utilized for helicopter flight require leading edge weights to provide blade chordwise balance and maintain rotor inertia. The weights are typically mounted to the rotor blades by an adhesive, such that they become bonded to the blades. However, provision for the retention of helicopter rotor blade leading edge weights in a high centrifugal force field, after failure of the primary adhesive bond, is necessary, in order to prevent loosening of the weights and a potentially dangerous condition, which could result in a catastrophic failure of the rotor blade.
In the prior art, secondary mechanical retention of the weights is usually accomplished by mechanical fastening. For example, fittings are often riveted directly to the rotor blade spar, and the weights are mounted, usually with studs and nuts, to the tip weight fitting. Other methods include wrapping some or all of the fibers of a composite spar through a slot or around a hook in the weight, or attaching the weight to the spar with bolts and/or rivets. Unfortunately, these kinds of prior art methods involve laborious manufacturing procedures, extensive employment of hardware, and a corresponding increase in weight beyond that necessary to balance the rotor. Furthermore, the use of bolts and rivets interrupts the fibers of a composite spar or creates stress concentrations in a metal spar, both of which conditions should be avoided.
Consequently, what is needed is a simple mechanical solution for retaining helicopter rotor leading edge weights, which requires little or no additional hardware, is substantially fail-safe, and does not complicate the winding of the spar.